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Monitoring the Environment During West Point Restoration

By April 28, 2017May 2nd, 2017No Comments

DSC_0191 - CopyKing County shared good news April 27 that West Point Treatment Plant is back online. Employees and contractors worked around the clock to restore critical mechanical and electrical systems that were damaged by severe flooding on Feb. 9.

Whenever clean water infrastructure is affected, King County Wastewater Treatment Division (WTD) gets in front of environmental monitoring. The scale of the West Point incident called for increased environmental monitoring and close coordination with the State Department of Ecology.

King County knows how much people in our region care about the environment, including our waters. We are answering questions, addressing concerns, and providing information about our environmental monitoring efforts as West Point is restored.  WTD’s West Point Restoration page includes all progress updates, plans, reports and data.

Here is a snapshot of current observations.

Treatment level increases with restoration progress

During the seven weeks immediately following the Feb. 9 event, wastewater entering the plant was screened to remove garbage, some solids were settled, and the effluent was disinfected to kill bacteria and other pathogens before discharge.

By March 30, as restoration activities progressed at West Point operators were able to start sending about 30 million gallons per day (mgd) of primary treatment effluent into the secondary treatment process. A week later, by April 6, that volume doubled to 60 mgd.

4-27-17 (29 mg-L TSS)

Treated effluent from April 27, 2017

Today, the plant can again function at its full hydraulic capacity, sending up to 440 million gallons of wastewater and stormwater through the treatment process.


Comparison of typical samples of incoming wastewater (raw sewage), secondary treated wastewater, highly treated wastewater and drinking water.


Environmental monitoring

Beach monitoring was carried out daily after the Feb. 9 and Feb. 15/16 emergency bypasses. Beaches in the area have remained open since Feb. 21. Field scientists are monitoring six beaches between West Seattle and Carkeek Park weekly. Beach samples continue to meet water quality standards for bacteria.


The West Point plant has its own onsite laboratory where lab specialists sample and test flows entering and leaving the plant to make sure discharges to Puget Sound have met all permit requirements. We expect to reach full compliance with our environmental permits by mid-May, or possibly sooner.

Out in Puget Sound, King County’s Environmental Lab conducts weekly  water quality sampling at four stations near West Point during treatment plant restoration, rather than the standard biweekly sampling. Water quality remains within seasonal ranges and standards for several measurements of health, including bacteria, nutrients, and dissolved oxygen.


Bacteria levels at stations in Puget Sound remain well within water quality standards. Data for additional parameters, along with plans and reports, are available online.

The Environmental Lab analyzes West Point discharges for metals and other pollutants. Results indicate the treatment process is successfully removing pollutants.

Our oceanographer has mapped historic sampling data and models to show how highly treated wastewater from the West Point deep water outfall disperses with tidal flow in Puget Sound. Generally, the effluent plume follows a strong north-south orientation.


Later this summer, field scientists will collect and analyze sediment samples from the vicinity of the outfall area as part of our permit requirement.

Jim through the window

Keeping people up to date

King County knows that people want to understand any environmental effects of the West Point incident – or any incident that affects our waters. As our hard-working employees and contractors continue repairs and restoration, we will continue to monitor the treatment process and environmental health.

We are striving to be as open and transparent as possible with the public, our regulators, and employees. We are reporting facts when we know them and informing agencies or groups that may be affected as soon as possible – including tribes, local health and parks departments, beach-goers and others.

Where can you get the most recent information about West Point?

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Contact us via phone or email at: 206-477-5371 or